The present invention relates to automatic ice making machines, and more particularly to a compact automatic ice making machine where the ice making evaporator is defrosted in a harvest mode by cool refrigerant vapor.
Automatic ice making machines rely on refrigeration principles well-known in the art. During an ice making mode, the machines transfer refrigerant from the condensing unit to the evaporator to chill the evaporator and an ice-forming evaporator plate below freezing. Water is then run over or sprayed onto the ice-forming evaporator plate to form ice. Once the ice has fully formed, a sensor switches the machine from an ice production mode to an ice harvesting mode. During harvesting, the evaporator must be warmed slightly so that the frozen ice will slightly thaw and release from the evaporator plate into an ice collection bin. To accomplish this, most prior art ice making machines use a hot gas valve that directs hot refrigerant gas routed from the compressor straight to the evaporator, bypassing the condenser.
In a typical automatic ice making machine, the compressor and condenser unit generates a large amount of heat and noise. As a result, ice machines have typically been located in a back room of an establishment, where the heat and noise do not cause as much of a nuisance. This has required, however, the ice to be carried from the back room to where it is needed. Another problem with having the ice machine out where the ice is needed is that in many food establishments, space out by the food service area is at a premium, and the bulk size of a normal ice machine is poor use of this space.
Several ice making machines have been designed in an attempt to overcome these problems. In typical xe2x80x9cremotexe2x80x9d ice making machines, the condenser is located at a remote location from the evaporator and the compressor. This allows the condenser to be located outside or in an area where the large amount of heat it dissipates and the noise from the condenser fan would not be a problem. However, the compressor remains close to the evaporator unit so that it can provide the hot gas used to harvest the ice. While a typical remote ice making machine solves the problem of removing heat dissipated by the condenser, it does not solve the problem of the noise and bulk created by-the compressor.
Other ice machine designs place both the compressor and the condenser at a remote location. These machines have the advantage of removing both the heat and noise of the compressor and condenser to a location removed from the ice making evaporator unit. For example, U.S. Pat. No. 4,276,751 to Saltzman et al. describes a compressor unit connected to one or more remote evaporator units with the use of three refrigerant lines. The first line delivers refrigerant from the compressor unit to the evaporator units, the second delivers hot gas from the compressor straight to the evaporator during the harvest mode, and the third is a common return line to carry the refrigerant back from the evaporator to the compressor. The device disclosed in the Saltzman patent has a single pressure sensor that monitors the input pressure of the refrigerant entering the evaporator units. When the pressure drops below a certain point, which is supposed to indicate that the ice has fully formed, the machine switches from an ice making mode to a harvest mode. Hot gas is then piped from the compressor to the evaporator units.
U.S. Pat. No. 5,218,830 to Martineau also describes a remote ice making system. The Martineau device has a compressor unit connected to one or more remote evaporator units through two refrigerant lines: a supply line and a return line. During an ice making mode, refrigerant passes from the compressor to the condenser, then through the supply line to the evaporator. The refrigerant vaporizes in the evaporator and returns to the compressor through the return line. During the harvest mode, a series of valves redirect hot, high pressure gas from the compressor through the return line straight to the evaporator to warm it. The cold temperature of the evaporator converts the hot gas into a liquid. The liquid refrigerant exits the evaporator and passes through a solenoid valve and an expansion device to the condenser. As the refrigerant passes through the expansion device and the condenser it vaporizes into a gas. The gaseous refrigerant then exits the condenser and returns to the compressor.
One of the main drawbacks of these prior systems is that the long length of the refrigerant lines needed for remote operation causes inefficiency during the harvest mode. This is because the hot gas used to warm the evaporator must travel the length of the refrigeration lines from the compressor to the evaporator. As it travels, the hot gas loses much of its heat to the lines"" surrounding environment. This results in a longer and more inefficient harvest cycle. In addition, at long distances and low ambient temperatures, the loss may become so great that the hot gas defrost fails to function properly at all.
Some refrigeration systems that utilize multiple evaporators in parallel have been designed to use hot gas to defrost one of the evaporators while the others are in a cooling mode. For example, in a grocery store with multiple cold and frozen food storage and display cabinets, one or more compressors may feed a condenser and liquid refrigerant manifold which supplies separate expansion devices and evaporators to cool each cabinet. A hot gas defrost system, with a timer to direct the hot gas to one evaporator at a time, is disclosed in U.S. Pat. No. 5,323,621. Hot gas defrosting in such systems is effective even though the compressor is located remotely from the evaporators due to the large latent heat load produced by the refrigerated fixtures in excess of the heat required to defrost selected evaporator coils during the continued refrigeration of the remaining fixtures. While there are some inefficiencies and other problems associated with such systems, a number of patents disclose improvements thereto, such as U.S. Pat. Nos. 4,522,037 and 4,621,505. These patents describe refrigeration systems in which saturated refrigerant gas is used to defrost one of several evaporators in the system. The refrigeration systems include a surge receiver and a surge control valve which allows hot gas from the compressor to bypass the condenser and enter the receiver. However, these systems are designed for use with multiple evaporators in parallel, and would not function properly if only a single evaporator, or if multiple evaporators in series, were used. Perhaps more importantly, these systems are designed for installations in which the cost of running refrigerant lines between compressors in an equipment room, an outdoor condenser, and multiple evaporators in the main part of a store is not a significant factor in the design. These refrigeration systems would not be cost effective, and perhaps not even practicable, if they were applied to ice making machines.
A good example of such a situation is U.S. Pat. No. 5,381,665 to Tanaka, which describes a refrigeration system for a food showcase that has two evaporators in parallel. A receiver supplies vaporous refrigerant to the evaporators through the same feed line as is used to supply liquid refrigerant to the evaporators. The system has a condenser, compressor and evaporators all located separately from one another. Such a system would not be economical if applied to ice machines where different sets of refrigerant lines had to be installed between each of the locations of the various parts. Moreover, if the compressor and its associated components were moved outdoors to be in close proximity to a remote condenser, the system would not be able to harvest ice at low ambient temperature because the receiver would be too cold to flash off refrigerant when desired to defrost the evaporators.
U.S. Pat. No. 5,787,723 discloses a remote ice making machine which overcomes the drawbacks mentioned above. One or more remote evaporating units are supplied with refrigerant from a remote condenser and compressor. Moreover, if a plurality of evaporating units are used, they can be operated independently in a harvest or ice making mode. The heat to defrost the evaporators in a harvest mode is preferably supplied from a separate electrical resistance heater. While electrical heating elements have proved satisfactory for harvesting ice from the evaporator, they add to the expense of the product. Thus, a method of harvesting the ice in the remote ice machine of U.S. Pat. No. 5,787,723 without electrical heating elements would be a great advantage. An ice making machine that includes a defrost system that utilizes refrigerant gas and can be used where the system has only one evaporator, or an economically installed system with multiple evaporators that also operates at low ambient conditions, would also be an advantage.
Another drawback to conventional ice making machines is their large size. In order to produce sufficient quantities of ice, large components are needed. A large cabinet is needed to house all of these components. When an ice machine is placed on top of a large ice bin in the back room of an establishment, its size is not much of a problem. However, as noted above, space out in the food service area, where the ice is needed, is often at a premium.
In addition, many ice machines are selected so that they will produce ice at a rate which meets overall daily demand at their location. However, often the demand for ice hits a peak, such as lunch time at a drive-up window on a hot day. It is not practical to install an ice machine at the drive-up window that can meet peak demand. Rather, it is more practical to have a smaller capacity ice machine and a storage bin that can accumulate ice in advance of peak demand. The storage bin is frequently built into the top of an ice and beverage dispenser. It would be advantageous if the ice machine were to sit on top of the dispenser and discharge into the bin. That would eliminate the need to transport ice from where it is produced into the top of the ice and beverage dispenser. However, the distance from the counter top where the dispenser is located to the top of the ceiling then limits how tall the combined ice machine and dispenser can be.
It would be of further advantage if the ice machine and bin arrangement allowed for ice to be dumped into the bin from a bucket filled from a different location to meet peak demand. Thus it would be beneficial if the ice machine could be configured to have a smaller xe2x80x9cfootprintxe2x80x9d than the standard size opening on top of an ice storage area of an ice and beverage dispenser. Even if it is not necessary to dump extra ice into a storage bin underneath an ice machine, it would be beneficial if an ice machine were small enough so that a person could have access to clean the dispenser. Standard dispensers are 22, 24, 30 and 42 inches wide, and often about 24-28 inches deep. The ice storage bin may have an internal depth of less than 27 inches. Therefore, it would be beneficial if the cabinet of an ice machine were less than 18 inches deep, and more preferably less than 16 inches deep.
Once an ice machine is installed on top of an ice and beverage dispenser, it is cumbersome to service the ice machine from its rear. Thus, it would also be beneficial if components that may require service or exchange were accessible from the front of the machine. Water pumps have conventionally been located in the front of ice machines so that they can be replaced easily if needed. However, it is desirable to keep the motor of a pump assembly outside of the compartment where the water is being frozen into ice, both to protect the motor from getting wet, and to remove the possible source of contamination associated with a motor. Locating the pump motor outside of the water compartment, but arranging it so that the pump assembly could be removed from the front of the machine, if needed, especially in a compact machine, would be very desirable.
An ice making machine has been invented which includes one or more of the foregoing advantageous features. In a preferred embodiment, all of the foregoing advantages are met in one ice machine. In the preferred embodiment, the compressor and condenser are remote from the evaporator but the apparatus does not require electrical heaters to heat the ice-forming mold, nor does it require hot gas to travel to the evaporator from the compressor. In addition, the refrigeration system will function in low ambient conditions, and is not expensive to install. A preferred machine has a footprint less than 18 inches deep, and has the water pump motor located outside of the water compartment, yet the pump assembly can still be removed from the front of the machine for service.
In one aspect, the invention is an ice making machine comprising: a) a water system including a pump, an ice-forming mold and interconnecting lines therefore; and b) a refrigeration system including a compressor, a condenser, an expansion device, an evaporator in thermal contact with the ice-forming mold, and a receiver, the receiver having an inlet connected to the condenser, a liquid outlet connected to the expansion device and a vapor outlet connected by a valved passageway to the evaporator.
In a second aspect, the invention is a method of making cubed ice in an ice making machine comprising the steps of: a) compressing vaporized refrigerant, cooling the compressed refrigerant to condense it into a liquid, feeding the condensed refrigerant through an expansion device and vaporizing the refrigerant in an evaporator to create freezing temperatures in an ice-forming mold to freeze water into ice in the shape of mold cavities during an ice making mode; and b) heating the ice making mold to release cubes of ice therefrom in a harvest mode by separating vaporous and liquid refrigerant within a receiver interconnected between the condenser and the expansion device and feeding the vapor from the receiver to the evaporator.
In a third aspect, the invention is an ice making apparatus in which an evaporator is located remotely from a compressor and a condenser comprising: a) a condensing unit comprising the condenser and the compressor; b) an ice making unit comprising i) a water system including a pump, an ice-forming mold and interconnecting lines therefor; and ii) a portion of a refrigeration system including the evaporator in thermal contact with the ice-forming mold, a receiver and a thermal expansion device; and c) two refrigerant lines running between the condensing unit and the ice making unit comprising a suction line and a feed line, the suction line returning refrigerant to the compressor and the feed line supplying refrigerant to the ice making unit; d) the receiver having an inlet, a liquid outlet and a vapor outlet, the inlet being connected to the feed line, the liquid outlet being connected to the expansion device, which in turn is connected to the evaporator, and the vapor outlet being connected by a valved passageway directly to the evaporator.
In a fourth aspect, the invention is an ice making machine comprising: a) a water system including a pump, an ice-forming mold and interconnecting lines therefore; and b) a refrigeration system including a compressor, a condenser, an expansion device, and evaporator in thermal contact with said ice-forming mold, and a plurality of receivers, the receivers each having an inlet connected to the condenser, a liquid outlet connected to the expansion device and a vapor outlet connected by a valved passageway to the evaporator, and a receiver equalizer line interconnecting the receivers, the pump, ice-forming mold, evaporation and receivers being contained within a cabinet having a depth, a width and a height and at least one of its depth, width or height being less than 18 inches.
In a fifth aspect, the invention is an ice making apparatus in which an evaporator is located remotely from a compressor and a condenser comprising: a) a condensing unit comprising said condenser and said compressor; b) an ice making unit comprising i) a water system including a pump, an ice-forming mold and interconnecting lines therefore; and ii) a portion of a refrigeration system including said evaporator in thermal contact with said ice-forming mold, a plurality of receivers and a thermal expansion device; and c) two refrigerant lines running between the condensing unit and the ice making unit comprising a suction line and a feed line, the suction line returning refrigerant to the compressor and the feed line supplying refrigerant to the ice making unit; wherein the receivers each have an inlet, a liquid outlet and a vapor outlet, the inlet being connected to the feed line, the liquid outlet being connected to the expansion device, which in turn is connected to the evaporator, and the vapor outlet being connected by a valved passageway directly to the evaporator, and wherein the ice making unit is contained in a cabinet having a depth of less than 18 inches.
In a sixth aspect, the invention is an ice making apparatus in which an evaporator is located remotely from a compressor and a condenser comprising: a) a condensing unit comprising said condenser and said compressor; b) an ice making unit comprising i) a cabinet having a depth of less than 18 inches; ii) a water system including a pump, an ice-forming mold and interconnecting lines therefore inside said cabinet; and iii) a portion of a refrigeration system including said evaporator in thermal contact with said ice-forming mold, at least one receiver and a thermal expansion device inside said cabinet; and c) two refrigerant lines running between the condensing unit and the ice making unit comprising a suction line and a feed line, the suction line returning refrigerant to the compressor and the feed line supplying refrigerant to the ice making unit; d) wherein the at least one receiver has an inlet, a liquid outlet and a vapor outlet, the inlet being connected to the feed line, the liquid outlet being connected to the expansion device, which in turn is connected to the evaporator, and the vapor outlet being connected by a valve passageway directly to the evaporator, and further wherein the ice making unit is able to produce at least 500 pounds of ice per day under ARI standard rating conditions of 90xc2x0 F. ambient temperature and 70xc2x0 F. ambient inlet water temperature.
In the seventh aspect, the invention is a combination of an ice making unit and an ice and beverage dispenser comprising: a) an ice and beverage dispenser having an ice storage bin in the top thereof with a internal bin depth, and b) an ice making unit housed in a cabinet placed on top of the ice storage bin, the cabinet having a depth, the depth of the ice making unit being at least 8 inches less than the internal depth of the ice storage bin.
In an eighth aspect, the invention is a compact ice making unit comprising: a cabinet, a water system inside the cabinet, including a water pump, an ice-forming mold and interconnecting lines therefore, and a portion of a refrigeration system including an evaporator in thermal contact with the ice-forming mold, at least one receiver and a thermal expansion device, wherein the cabinet occupies a volume and wherein the ice making unit produces cubed ice at a rated capacity of 2500 pounds per day or less under ARI standard test conditions of 90xc2x0 F. ambient temperature and 70xc2x0 F. ambient inlet water temperature, and wherein the ratio of ice production rate to cabinet volume is at least 125 pounds of ice/day/ft3.
In a ninth aspect, the invention is an ice making unit comprising: a) a cabinet having a front panel covering a front panel opening, a water compartment behind the front panel, a mechanical compartment and a divider between the mechanical compartment and the water compartment, b) a water system inside the cabinet including a pump assembly, an ice-forming mold, a water reservoir, and interconnecting lines therefore, c) a portion of a refrigeration system including an evaporator in thermal contact with said ice-forming mold, at least one receiver and a thermal expansion device inside the cabinet, and d) the pump assembly comprising a motor and a pump housing, the pump assembly extending through the divider such that the pump motor is in the mechanical compartment and the pump housing is in the water compartment, and wherein the pump assembly can be removed through the front panel opening and replaced without the use of tools.
The use of cool refrigerant vapor from a receiver to defrost an evaporator has several advantages. It eliminates the need for an electrical heating unit, or the problems associated with piping hot gas over a long distance in a remote compressor configuration. Since the cool vapor is located inside the evaporator coil, there is excellent heat transfer to those parts of the system that need to be warmed. The system can be used to defrost the evaporator where there is only one evaporator in the refrigeration system, or multiple evaporators in series, as well as evaporators in parallel.
Since hot gas is not needed for the defrost, the compressor can be located remotely from the ice-forming evaporator. As a result, the cabinet holding the evaporator can be smaller. Thus, the footprint of the ice making machine can be reduced. Using two receivers, as in a preferred embodiment of the invention, allows the receivers to have a smaller diameter, thus allowing for a narrower ice machine. This allows the ice machine to be placed on top of a dispenser, yet not cover the entire ice storage bin opening. The open space between the front of the bin and the front of the ice machine can be covered with a removable cover, allowing extra ice to be poured into the ice storage bin from a bucket to meet peak demand, and allowing access to the ice storage bin for cleaning and/or sanitizing operations. The preferred embodiment also has a unique water pump assembly with the water pump motor located outside of the water compartment of the ice making machine. The unique water pump assembly can be removed through the face of the machine without the use of any tool.
These and other advantages of the invention will be best understood in view of the attached drawings.